In a significant advance in micro-mechanical device technology, a micron-sized hinge was developed. The hinge, which can be used for forming hinged plates, has provided the art with a means for fabricating complex micro-electro-mechanical systems (MEMS) and micro-opto-electro-mechanical systems (MOEMS) devices. Presently, micron-sized analogs of many macro-scale devices can be fabricated. Applications of MEMS and MOEMS include, for example, data storage devices, laser scanners, printer heads, magnetic heads, micro-spectrometers, scanning-probe microscopes, near-field optical microscopes, optical scanners, optical modulators, micro-lenses, optical switches, and micro-robotics.
Forming a MEMS or MOEMS device begins with patterning hinged plates in appropriate locations on a substrate. As patterned, the various hinged plates lie flat on top of the substrate. Assembling the device involves lifting the unhinged end of each plate off of the substrate. For many devices, assembly requires that the hinged plates are placed in a substantially perpendicular orientation relative to the substrate.
An operator can assemble MEMS and MOEMS devices using a microprobe station to lift the various hinged plates into their required position. But, manual assembly of a large number of such devices, or even a single complex device, is impractical for commercial scale operation. Manual assembly of such devices limits the utility of the technology to little more than a laboratory curiosity.
Coupling actuators with micro-mechanical devices allows for automated assembly. A typical assembly system uses a "vertical" actuator that imparts an upwardly-directed force to lift a hinged plate off of the substrate. One such actuator is described by Cowan et al. in "Vertical Thermal Actuator for Micro-Opto-Electro-Mechanical Systems," v.3226, SPIE, pp. 137-46 (1997). Conventional actuators, such as described by Cowan et al., are limited in their usefulness, however, because they cannot rotate or lift hinged plates substantially more than forty-five degrees out of plane in a single actuation step. Nor has it been possible to achieve lift angles substantially greater than forty-five degrees only using an assembly motor.
Lift angles substantially greater than forty-five degrees are achieveable with a dual-stage assembly system. A dual-stage assembly system typically consists of a vertical actuator and an assembly motor. The vertical actuator lifts the hinged micro-mechanical device off of the substrate to a maximum angle not substantially greater than forty-five degrees. The assembly motor, which has a drive arm connected to a lift arm of the micro-mechanical device, completes the lift. One such dual-stage assembly system is disclosed by Reid et al. In "Automated Assembly of Flip-Up Micromirrors," Transducers '97, Int'l Conf. Solid-State Sensors and Actuators, pp. 347-50 (1977).
The dual-stage assembly system is complex, however, thereby increasing the cost of chips containing MEMS and MOEMS devices assembled thereby. As such, there is a need for a single-stage assembly system for micro-mechanical devices capable of rotating a hinged plate as much as ninety degrees out-of-plane.